Is the Zero-Wait Policy Always Optimum for Information Freshness (Peak Age) or Throughput?

The zero-wait (ZW) policy is widely held to achieve maximum information “freshness”, i.e., to achieve minimum peak age (PA) and maximum throughput, for real-time Internet-of-Things applications. In this letter, it was shown through a series of experiments that the ZW policy is not necessarily the optimum policy for freshness or throughput in all real-world scenarios. First, the effect of delay on the ZW policy was shown on a local area network (LAN). Afterward, the server was located on the Internet, and it was shown that the ZW policy incurred a two-fold PA and throughput performance degradation compared with continuously sending status updates.